1. Field of the Invention
Example embodiments of the present invention relate to a method of forming a thin film, a method of manufacturing a gate structure using the same and a method of manufacturing a capacitor using the same. More particularly, example embodiments of the present invention relate to a method of forming a thin film including hafnium oxide, a method of manufacturing a gate structure using the same and a method of manufacturing a capacitor using the same.
2. Description of the Related Art
A thin film of a semiconductor device has been recently formed using a material having a high dielectric constant. For example, a gate insulation layer of a metal oxide semiconductor (MOS) transistor, a dielectric layer of a capacitor, or a dielectric layer of a flash memory device may be formed using a material having a high dielectric constant. When a thin film is formed using a material having a high dielectric constant, the thin film may have a thin equivalent oxide thickness (EOT). Additionally, a leakage current generated between a gate electrode and a channel region or between a lower electrode and an upper electrode may decrease when the thin film is employed as the gate insulation layer or the dielectric layer. Further, a coupling ratio of the flash memory device may be enhanced when the thin film is used as the dielectric layer of the flash memory device.
Examples of materials having high dielectric constants may include tantalum oxide (Ta2O5), yttrium oxide (Y2O3), hafnium oxide (HfO2), zirconium oxide (ZrO2), niobium oxide (Nb2O5), barium titanium oxide (BaTiO3), strontium titanium oxide (SrTiO3), etc. When a thin film includes hafnium oxide, the thin film may be formed using a hafnium precursor and an oxidizing agent.
Examples of a hafnium precursor for forming a thin film of hafnium oxide may include tetrakis(ethylmethylamino) hafnium (TEMAH) represented by Hf(NC2H5CH3)4 or hafnium tetra-tert-butoxide (HTTB) represented by Hf(OC4H9)4. When a thin film including hafnium oxide is formed using TEMAH, the thin film may have good dielectric characteristic. However, TEMAH has a relatively low saturation vapor pressure. For example, when TEMAH is heated at a temperature of about 90° C. in a canister to be vaporized, TEMAH has a saturation vapor pressure of about 1 Torr. Because of the low saturation vapor pressure, process time for providing the hafnium precursor into a chamber increases. An increase in process time may cause a throughput reduction of a semiconductor manufacturing process. In addition, when TEMAH is heated to a temperature higher than about 90° C., in order to enhance the saturation vapor pressure, TEMAH may be denatured.
HTTB has a relatively high saturation vapor pressure. For example, HTTB has a saturation vapor pressure greater than or equal to about 5 Torr at a temperature of about 90° C. However, HTTB may rapidly vaporize at an elevated temperature, so that HTTB does not react with the oxidizing agent and hafnium oxide is not formed.